Multiple peer-reviewed sources support the physiological claims in the post. Whey protein serves as a highly efficient source for muscle protein synthesis, primarily due to its rapid digestion and rich essential amino acid profile, and the high concentration of leucine in whey protein specifically stimulates muscle growth.

Being a rapidly digested protein with a high leucine content, whey has been shown to stimulate MPS more than equal amounts of casein and soy in the first hours after exercise.

On dosing, the Georgia State University summary of the ISSN position stand states that the amount of protein to consume surrounding training is 0.4 to 0.5 g/kg of lean body mass, and for most individuals, 20 to 40 grams of protein is adequate . Peloton's summary from a registered dietitian similarly notes that typically 20 to 40 grams of protein and 30 to 90 grams of carbs is ideal, though the ranges are wide and depend on the person, workout, and goals .

On timing, evidence contradicts the "immediate drink" urgency. Secondary summaries of the literature note that modern research demonstrates that the anabolic window extends much longer than originally believed, and if protein was eaten within 3 to 4 hours before training, post-workout timing becomes far less critical for muscle protein synthesis . A Healthline synthesis of the research notes that a 2017 study found that pre and post-workout protein intake both produce similar muscle adaptations, suggesting that pre-workout protein could suffice and immediate post-workout intake isn't much better . The Schoenfeld et al. meta-analysis is described as having pooled 23 trials, where the timing effect on muscle growth disappeared when total daily protein was accounted for .